What is the formula to calculate the rating of a thermal
over load relay

Answers were Sorted based on User's Feedback



What is the formula to calculate the rating of a thermal over load relay..

Answer / barkha jha

At starting motor draws current 5 to 6 times of the flc so
overload relay setting is done this kept on mind.for e.g
3.7 kw motor the
FLC is 8 amps. we can select the relay 6A-10A range.
tripping setting is 90 % of FLC

Is This Answer Correct ?    38 Yes 7 No

What is the formula to calculate the rating of a thermal over load relay..

Answer / jayakumar.k

There is no General formula .but the general practice is
motor FLC should be the setting . for e.g 3.7 kw motor the
FLC is 8 amps. we can select the relay 6A-10A range. 8Amps
shoud be the trip setting.

Is This Answer Correct ?    25 Yes 17 No

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